The present invention broadly relates to sheet feeders for printers and, more specifically, pertains to a new and improved construction of an individual sheet feeder device for pre-printed forms or data recording sheets.
Generally speaking, the sheet feeder devices of the present invention is intended to be employed in conjunction with a conventional printer for individually feeding pre-printed forms, data recording sheets, tickets or the like to a print platen or print roller of the conventional printer and comprises at least one pre-printed form guide means for guide channel leading to the printer platen and at least one position sensor arranged in the region of the pre-printed form guide means.
In other words, the sheet feeder device or sheet feeder accessory device of the present invention for a conventional printer comprises a sheet feed guide structure or channel for guiding a manually-inserted sheet or pre-printed form to be printed into the printer.
The invention also pertains to the employment of the inventive sheet feeder device in conjunction with a conventional printer as a data-recording printer.
Measuring instruments are becoming increasingly computer-controlled or microprocessor-controlled in the course of general technological progress. Consequently, the need for recording measurement results is increasing, on the one hand, while the demands upon the quality of such recording as well as upon the quantity of data to be recorded are rapidly increasing, on the other hand.
Form printers or so-called ticket printers, i.e. printers for filling in print fields of pre-printed forms, are widely employed as data recording printers, e.g. in clinical analysis. Such printers are specially designed printers often intended for only one specific application and are usually designed around the particular form or ticket to be printed. At least the dimensions of the paper guide mechanism, the printer platen or roll and often also the external dimensions of the entire printer are based upon the particular form or ticket employed. Any modification of the format of the form or ticket in the course of further development also requires intrusive modifications to the data recording printer itself, up to and including complete redesign. Such format modifications of a form or ticket become necessary when more comprehensive supplementary data is to be printed out or when the decision is taken to broaden the functionality of the associated measuring instrument.
It is increasingly demanded in the course of this general technological development that data recording printers also be capable of doing graphics, i.e. that digitally transmitted measurement results be printed out in the form of graphical representations.
Matrix printers have been successful as the majority of data recording printers, since they fulfill the manifold demands at justifiable expense. So-called pretty printers, i.e. letter quality printers, near letter quality printers, correspondence printers or printers employing type elements, which are usually of more complicated design than matrix printers, are also occasionally employed as data recording printers. Such printers can provide hard copy output of the recorded data in typewriter quality or nearly so.
On the other hand, the same types of printer are widely employed as universal printers both in administrative and technological fields. The control of such generally employable matrix and type-element printers is usually effected by control characters which are, in part, received through the data channels conjointly with the data to be printed out (software control) and, in part, over separate control channels or lines (hardware control). Individual control commands, such as the START command or the PRINT/STOP command, can usually also be manually input with special function keys. Paper infeed can generally also be performed manually by employing function keys provided for this purpose. Externally controlled devices for automatic paper feed are also commonly employed.
The line feed command or control character LF and the select switch command or control character SEL are particularly important commands for functional control of a printer. The line feed command or function LF advances or increments the paper by a predeterminate amount (a so-called print line) and, after termination of printing, ejects the paper or carrier of printed data. The select command or function SEL opens or closes one or more data channels from the source of data to the printer.